Jack Holdzkom has reminded me that we have just passed the 47th year since the loss of the Soviet NOVEMBER Class SSN on 12 April 1970.

Here's what was posted several years ago:

When the NOVEMBER Class Soviet SSN (K-8) sank in the Bay of Biscay (47-25N, 19-40W) on 12 (not 11) April 1970 as the result of fires, an associated collapse event was acoustically detected by a SOSUS array in the western Atlantic at 04:04:44Z.

The K-8 sank, down by the stern, with 52 of the crew still on board. They had previously been evacuated to a Soviet surface ship but were ordered back on board by the “Beach.” Shortly thereafter, the K-8 – on the surface in rough seas – lost stability and sank.

Analysis of the bubble-pulse component produced by the collapse (13 Hz) indicated the NOVEMBER collapse occurred at a depth of 2,020-feet (900 psi) with an energy release equal to the explosion of 1,050 pounds of TNT at that depth. Based on the MIKE and STERLET data, that event is assessed to have been the collapse of the NOVEMBER torpedo room bulkhead and/or the torpedo room pressure-hull. The published test-depth of the NOVEMBER Class was 985-feet.

To the above, it can be added - based on the now known temporal asymmetry of the compression and expansion phases of a collapse event - that complete destruction of the NOVEMBER occurred in 0.013 seconds (13 milliseconds), even faster than SCORPION (37 milliseconds) but then the NOVEMBER collapsed 500-feet deeper than SCORPION, and greater depth means greater pressure: 220 psi greater.